Namespace/stream management

ABSTRACT

A method includes: receiving logical streams from a plurality of namespaces; determining characteristics of logical streams associated with the plurality of namespaces; selecting a configurable assignment mode; and assigning the logical streams associated with the plurality of namespaces to a plurality of hardware streams to access physical storage blocks associated with a data storage device based on the characteristics of the logical streams and the configurable assignment mode. A number of hardware streams to access the physical storage blocks associated with the data storage drive is fixed, and a number of logical streams associated with the plurality of namespaces is varied depending on I/O processes running on a host computer.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefits of and priority to U.S. ProvisionalPatent Application Ser. No. 62/508,829 file May 19, 2017, the disclosureof which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to multi-streaming capablestorage devices, more particularly, to a system and method for mappingstreams to storage blocks based on namespaces.

BACKGROUND

Multi-streaming of a solid-state drive (SSD) enables related data to bestored on the same physical erase blocks under the belief that thesimilar stored data can have similar invalidation times, and can begarbage collected more efficiently. Thus, multi-streaming can reduce awrite amplification factor (WAF) of the SSD.

Modern SSDs implemented with the multi-streaming feature typically havea limited number of hardware streams available, for example 8 to 16hardware streams. However, modern SSDs are capable of housing manyindependent namespaces, and each namespace may have numerous logicalstreams. Conventional multi-streaming schemes that focuses onidentifying and merging streams do not take into account the associationof the logical streams to the affiliated namespaces.

SUMMARY

According to one embodiment, a method includes: receiving logicalstreams from a plurality of namespaces; determining characteristics oflogical streams associated with the plurality of namespaces; selecting aconfigurable assignment mode; and assigning the logical streamsassociated with the plurality of namespaces to a plurality of hardwarestreams to access physical storage blocks associated with a data storagedevice based on the characteristics of the logical streams and theconfigurable assignment mode. A number of hardware streams to access thephysical storage blocks associated with the data storage drive is fixed,and a number of logical streams associated with the plurality ofnamespaces is varied depending on I/O processes running on a hostcomputer.

According to another embodiment, a data storage device includes: aplurality of data storage blocks; and a stream mapper configured to:receive logical streams from a plurality of namespaces; determinecharacteristics of logical streams associated with the plurality ofnamespaces; select a configurable assignment mode; and assign thelogical streams associated with the plurality of namespaces to aplurality of hardware streams to access the plurality of data storageblocks based on the characteristics of the logical streams and theconfigurable assignment mode. A number of hardware streams to access thephysical storage blocks associated with the data storage drive is fixed,and a number of logical streams associated with the plurality ofnamespaces is varied depending on I/O processes running on a hostcomputer.

The above and other preferred features, including various novel detailsof implementation and combination of events, will now be moreparticularly described with reference to the accompanying figures andpointed out in the claims. It will be understood that the particularsystems and methods described herein are shown by way of illustrationonly and not as limitations. As will be understood by those skilled inthe art, the principles and features described herein may be employed invarious and numerous embodiments without departing from the scope of thepresent disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included as part of the presentspecification, illustrate the presently preferred embodiment andtogether with the general description given above and the detaileddescription of the preferred embodiment given below serve to explain andteach the principles described herein.

FIG. 1 shows a block diagram of an example stream-mapping system,according to one embodiment;

FIG. 2A shows an example proportional scheme for assigning logicalstreams to hardware streams, according to one embodiment;

FIG. 2B shows an example weighted proportional scheme for assigninglogical streams to hardware streams, according to one embodiment;

FIG. 3A shows an example fair and balanced scheme for assigning logicalstreams of namespaces to hardware streams, according to one embodiment;

FIG. 3B shows an example fair and balanced scheme for assigning logicalstreams of namespaces to hardware streams, according to anotherembodiment;

FIG. 4 shows an example even and proportional scheme for assigninglogical streams to hardware streams, according to one embodiment;

FIG. 5A shows an example of a hybrid auto-streaming scheme, according toone embodiment;

FIG. 5B shows an example of a hybrid auto-streaming scheme, according toanother embodiment;

FIG. 6 is a flowchart of an example fair and balanced mapping scheme,according to one embodiment;

FIG. 7 is a flowchart of an example proportional mapping scheme,according to one embodiment;

FIG. 8 is a flowchart of an example even and proportional mappingscheme, according to one embodiment;

FIG. 9 is a flowchart of an example hybrid auto-streaming mappingscheme, according to one embodiment.

The figures are not necessarily drawn to scale and elements of similarstructures or functions are generally represented by like referencenumerals for illustrative purposes throughout the figures. The figuresare only intended to facilitate the description of the variousembodiments described herein. The figures do not describe every aspectof the teachings disclosed herein and do not limit the scope of theclaims.

DETAILED DESCRIPTION

Each of the features and teachings disclosed herein can be utilizedseparately or in conjunction with other features and teachings toprovide a system and method for mapping streams to storage blocks basedon namespaces. Representative examples utilizing many of theseadditional features and teachings, both separately and in combination,are described in further detail with reference to the attached figures.This detailed description is merely intended to teach a person of skillin the art further details for practicing aspects of the presentteachings and is not intended to limit the scope of the claims.Therefore, combinations of features disclosed above in the detaileddescription may not be necessary to practice the teachings in thebroadest sense, and are instead taught merely to describe particularlyrepresentative examples of the present teachings.

In the description below, for purposes of explanation only, specificnomenclature is set forth to provide a thorough understanding of thepresent disclosure. However, it will be apparent to one skilled in theart that these specific details are not required to practice theteachings of the present disclosure.

Some portions of the detailed descriptions herein are presented in termsof algorithms and symbolic representations of operations on data bitswithin a computer memory. These algorithmic descriptions andrepresentations are used by those skilled in the data processing arts toeffectively convey the substance of their work to others skilled in theart. An algorithm is here, and generally, conceived to be aself-consistent sequence of steps leading to a desired result. The stepsare those requiring physical manipulations of physical quantities.Usually, though not necessarily, these quantities take the form ofelectrical or magnetic signals capable of being stored, transferred,combined, compared, and otherwise manipulated. It has proven convenientat times, principally for reasons of common usage, to refer to thesesignals as bits, values, elements, symbols, characters, terms, numbers,or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the below discussion, itis appreciated that throughout the description, discussions utilizingterms such as “processing,” “computing,” “calculating,” “determining,”“displaying,” or the like, refer to the action and processes of acomputer system, or similar electronic computing device, thatmanipulates and transforms data represented as physical (electronic)quantities within the computer system's registers and memories intoother data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission or display devices.

Moreover, the various features of the representative examples and thedependent claims may be combined in ways that are not specifically andexplicitly enumerated in order to provide additional useful embodimentsof the present teachings. It is also expressly noted that all valueranges or indications of groups of entities disclose every possibleintermediate value or intermediate entity for the purpose of an originaldisclosure, as well as for the purpose of restricting the claimedsubject matter. It is also expressly noted that the dimensions and theshapes of the components shown in the figures are designed to help tounderstand how the present teachings are practiced, but not intended tolimit the dimensions and the shapes shown in the examples.

The present disclosure describes a stream mapper of a data storagedevice for assigning hard-stream (that is SSD hardware-supported stream,herein also referred to as “hardware stream”) resources to namespacesbased on the affiliations of namespaces. Examples of the namespaceaffiliations include, but are not limited to, a number of namespaces, anumber of logical streams per namespace, the input/output patterns ofthe logical streams, and the use of the logical streams. The streammapper maps a large number of streams and namespaces as seen from a hostinto a limited number of hardware streams available from the datastorage device. The mapping scheme employed by the present stream mappercan take one or more of the following approaches including: a fair andbalanced approach, a proportional approach, a proportional and fairapproach, and a hybrid auto-stream approach.

FIG. 1 shows a block diagram of an example stream-mapping system,according to one embodiment. A data storage drive 100 (e.g., an SSD) isa multi-stream enabled drive including four namespaces NS 110 a, 110 b,110 c, and 110 d, and each of the four namespaces has one or morelogical streams 145, for example, w, x, y, and z. The stream-mappingsystem has a fixed number of hardware streams 155 to access physicalstorage blocks 160 associated with the data storage drive 100. Thenumber of logical streams 145 and the number of hardware streams 155 maybe different from each other. A stream mapper 150 maps the logicalstreams 145 of the namespaces to the hardware streams 155.

According to one embodiment, the stream mapper 150 can map the logicalstreams 145 based on various mapping schemes. The mapping schemesimplemented by the stream mapper 150 may dynamically change during aruntime depending on various operating conditions such as the workload,the number of namespaces and the number of logical and hardware streams.For example, the stream mapper 150 can employ one of a proportionalscheme, a fair and balanced scheme, an even and proportional scheme, anda hybrid auto-streaming scheme.

According to one embodiment, I/O traffic (e.g., I/O packets) fromnamespaces that have not been otherwise assigned to any stream may beassigned to a general I/O handler. In some ways, the general I/O handleraggregates I/O traffic similar to a stream, but the I/O data going intothe general I/O handler may not have unifying, common characteristicother than that it does not share characteristics with the otherstreams. This general purpose I/O handler may require a stream (or not),depending on the implementation. In cases where it requires a stream,the stream that is assigned to the general I/O handler is subtractedfrom the total hardware stream availability before specific streamassignment schemes are applied.

According to one embodiment, the stream mapper 150 can select namespacesto share hardware streams using auto-streaming and/or streamconsolidation techniques. Examples of stream assignment approaches thatthe stream mapper 150 can employ include, but are not limited to, a datawrite sequentially based approach, a data write frequency and recency(SFR) approach, a multi-queue approach, a round robin approach. Thelogical streams of the namespaces may be grouped together based on theirsimilarities of the data, for example, a write sequentiality, alifespan, a timing pattern, an I/O size, a file type (e.g., MS Excel,Word), etc. Various auto-streaming and/or stream consolidationtechniques are described in U.S. patent application Ser. No. 15/499,877filed Jul. 13, 2015 and entitled “Automatic Stream Detection &Assignment Algorithm,” Ser. No. 15/458,968 filed Oct. 26, 2016 andentitled “Method of Consolidating Data Streams for Multi-Stream EnabledSSDs,” and Ser. No. 15/344,422 filed Nov. 4, 2016 and entitled “SmartI/O Stream Detection based on Multiple Attributes,” the disclosures ofwhich are incorporated by reference.

Multiple namespace control employed by the stream mapper 150 enables aplurality of logical address spaces (LBA spaces) to be allocated to thedata storage drive 100 by handling the data storage drive 100 as if itwere a plurality of virtual drives. A write command from a host includesan identifier of a specific namespace. The stream mapper 150 candetermine the namespace to be accessed based on the identifier of thenamespace included in the write command. The host can thereby handle thevirtual drives of the data storage drive 100 without partitioning thelogical address space into a plurality of spaces, as if the data storagedrive 100 were a plurality of drives. The multi namespace control cantherefore reduce the total cost of ownership (TCO) on the host side.

In one embodiment, the stream mapper 150 can treat all logical I/Ostreams from a namespace as if they were a single stream (regardless ofthe number of logical streams from the namespace) and then analyzes andmerges the most similar namespaces at the hardware stream level.

According to one embodiment, the stream mapper can map logical streamsbased on a proportional scheme. According to the proportional scheme,the stream mapper 150 assigns to each namespace a number of hardwarestreams in proportion to its logical stream demands and/or read/writethroughput. For example, the number of logical streams can be used todetermine the proportion of the hardware streams to be assigned to eachnamespace. In another example, each of logical streams may be given aweight, and the weighted logical streams for each namespace may be usedto determine the proportion of the hardware stream assignment. One ormore namespaces may be merged if the number of namespaces is larger thanthe number of hardware streams available.

FIG. 2A shows an example proportional scheme for assigning logicalstreams to hardware streams, according to one embodiment. In thisexample, the namespace NS1 has 1 logical stream, the namespace NS2 has 8logical streams, the namespace NS3 has 64 logical streams, the namespaceNS4 has 2 logical streams, the namespace NS5 has 4 logical streams, andthe namespace 6 has 1 logical streams. The stream mapper 150 may treatthe logical streams without giving a weight. The total number of logicalstreams is 80. Depending on the proportionality, the namespace NS2 isassigned with 2 hardware streams, the namespace NS3 is assigned with 13hardware streams, and the namespace NS5 is assigned with 1 hardwarestream. The namespaces NS1, NS4, and NS6 are not assigned with anyhardware streams. After the logical streams of the NS2, NS3, and NS5 arecompleted or put on a hold, the hardware streams that are freed may bereassigned to the namespaces NS1, NS4, and NS6.

According to one embodiment, the namespace assignment based on theproportional scheme may be based on weighted logical streams. Eachlogical stream may be given a weight, and the weighted sum of thelogical streams for each namespace is factored in assigning the numberof hardware streams. Some logical streams may be given a higher weightthan other logical streams. Further, some namespaces may be given ahigher weight than other namespaces. For example, at least one logicalstream of each namespace may be given a higher weight based on athroughput of the logical streams. The logical streams with a highthroughput may get weighted higher than those with a lower throughput.Therefore, a namespace with a low number of high-throughput logicalstreams can get a share of the hardware streams when competing againstanother namespace with a high number of low-throughout logical streams.

FIG. 2B shows an example weighted proportional scheme for assigninglogical streams to hardware streams, according to one embodiment. In thepresent example, the total number of logical streams of the namespacesNS1-NS6 are 80 (1+8+64+2+4+1). The proportions of each namespace NS1-NS6are 0.0125, 0.1, 0.8, 0.025, 0.05, and 0.0125. The total I/O throughputsof each namespace NS1-NS6 are 12, 24, 64, 8, 8, and 4 Megabytes/seconds(MB/s). The throughput proportion of each namespace is its contributionto the whole throughput. That is, TP Proportions for NS1-NS6 are 0.1,0.2, 0.533, 0.067, 0.067, and 0.033. It is noted that the I/O throughputof each namespace may be measured using different metrics such as thenumber of data packets per a unit time slot. Based on these I/Othroughputs, the weighted number of logical streams for each namespaceis calculated as follows:

Weighted LS=(Throughput Proportion/LS Proportion)*Number of LS.

For example, the namespace NS1 has only 1 logical stream, but itsweighted logical stream is 8 ((0.1/0.125)*1). This implies that thelogical stream (only one) of the namespace NS1 is given a higher weightthan its number of logical streams because the I/O throughput for thelogical stream is higher compared the average I/O throughput of otherlogical streams that belong to other namespaces NS2-NS6. In anotherexample, the namespace NS3 has 64 logical streams, but its weightedlogical stream is 42.667 ((0.533/0.8)*64). This implies that the logicalstream of the namespace NS3 is given a lower weight compared its numberof logical streams because its I/O throughput is lower than the averageI/O throughput of other logical streams that belong to other namespacesNS1, NS2, and NS4-NS6. Based on the weighted logical streams, thehardware streams are assigned to each namespace NS1-NS6.

According to one embodiment, the stream mapper 150 may employ a fair andbalanced scheme. The stream mapper 150 divides hardware streams fairlyamongst the namespaces based on the number of namespaces, and nonamespace can have more hardware streams than the number of logicalstreams required. If there are more namespaces than hardware streams,some namespaces can be selected to share hardware streams. In someembodiments, if there are remaining hardware streams after giving eachnamespace a fair number of streams, the remaining hardware streams canbe assigned to the namespaces based on a proportional scheme asdiscussed above.

If there are more streams than namespaces, and the division of thestreams is unequal, then the stream mapper 150 assigns the remaininghardware streams to the namespaces based on a demand for the logicalstreams or I/O throughput. The fair and balanced scheme recognizes thatthe namespace is an ultimate determiner of data relatedness or closenesswhen all other factors for assigning or merging logical streams fail, orare unusable (or too fine-grained).

For a system having X hardware streams and Y namespaces, a floor valueis calculated by the number of hardware streams divided by the number ofnamespaces:

floor=integer[(number of hardware streams)/(number of namespaces)].

Depending on the value of the floor, the stream mapper 150 can applydifferent fair and balanced mapping schemes.

In one embodiment, when the floor value is larger than or equal to one,i.e., the number of available hardware streams is larger than or equalto the number of namespaces, the stream mapper 150 can assign eachnamespace with at least one hardware stream (i.e., fair assignment).Herein, the term “fair” or “fairly” indicates that the maximum number ofhardware streams assigned to a namespace does not exceed the number oflogical streams running in the namespace. After the fair assigning ofthe hardware streams to the namespaces based on the floor value, thestream mapper 150 can assign the remaining hardware streams to thenamespaces based on the remaining number of logical streams in eachnamespace.

FIG. 3A shows an example “fair and balanced” scheme for assigninglogical streams of namespaces to hardware streams, according to oneembodiment. In the present example, there are a total of 16 hardwarestreams available, and six namespaces (NS1 through NS6) are running.Therefore, the number of available hardware streams is larger than thenumber of namespaces, so the floor value is larger than or equal to one.

The namespace NS1 has 1 logical stream, the namespace NS2 has 8 logicalstreams, the namespace NS3 has 64 logical streams, the namespace NS4 has2 logical streams, the namespace NS5 has 5096 logical streams, and thenamespace 6 has 128 logical streams. These values are simply examplesfor illustration, and it is noted that any namespace may have any numberof associated logical streams. The floor value in this case is 2(integer (16/6)), therefore up to two hardware streams can be assignedto each of the namespaces. However, the namespace NS1 has only onelogical stream, therefore only one hardware stream is assigned to thenamespace NS1. This completes the assignment of the hardware streamsbased on the fairness, and a total of 11 hardware streams out of the 16available hardware streams are assigned.

Once the fair assignment is completed, the stream mapper 150 assigns theremaining hardware streams based on the “balance” of the logical streamsfor each namespace. The balanced assignment of the hardware streamsdepends on the number of logical streams for each namespace. Forexample, the namespace NS3 having 64 logical streams is assigned withall of the remaining 5 hardware streams based on a proportion of theremaining logical streams for each namespace (assuming otherwise equalthroughput). The namespaces NS1, NS2, NS4, NS5, and NS6 are not assignedwith any of the remaining hardware streams because they have arelatively smaller number of logical streams compared to the namespacesNS3, NS5, and NS6 (and throughput is assumed equal in the example). This“balanced” assignment of the remaining hardware streams completes themapping of the total of 16 hardware streams.

FIG. 3B shows an example fair and balanced scheme for assigning logicalstreams of namespaces to hardware streams, according to anotherembodiment. In this example, there are 8 hardware streams available, and14 namespaces, resulting in the floor being less than one. Therefore,some namespaces cannot be assigned with at least one hardware stream. Inthis case, instead of assigning a fair number of hardware streams toeach of the namespaces, the stream mapper 150 analyzes the I/O trafficpatterns of each namespace as a whole and merges some namespaces havingthe same or similar characteristics into a logical namespace cluster.The stream mapper 150 continues to merge the namespaces into namespaceclusters until the number of namespace clusters becomes equal to or lessthan the number of available hardware streams. The cluster-levelgrouping of namespaces by the stream mapper 150 reduces the number ofnamespace clusters so that each namespace cluster is assigned with afair number of hardware streams.

In the present example, the namespaces NS1, NS2, and NS33 are grouped,the namespaces NS5 and NS6 are grouped, and the namespaces NS7, NS8, andNS9 are grouped, and the namespaces NS11 and NS12 are grouped into arespective namespace cluster. The namespaces NS4, NS10, NS13, and NS14are not grouped, resulting in a single namespace cluster. Each of thenamespace clusters are assigned with a fair number of hardware streams,in this case one hardware stream. If any hardware streams remain afterthe fair assignment of the hardware streams to the namespace clusters,the remaining hardware streams may be assigned to one or more namespaceclusters based on the number of logical streams in the namespaceclusters for a balanced assignment.

According to yet another embodiment, the stream mapper can map logicalstreams based on an even and proportional scheme. The even andproportional scheme is particularly useful when the number of hardwarestreams is much larger than the number of namespaces. Herein, the term“even” or “evenly” indicates that the same number of hardware streamsare assigned to each namespace as a base number. The total number of theeven numbers assigned to the namespaces may not exceed the hardwarestreams available. In some cases, the even number may include a “fair”number as discussed above in the fair and balanced scheme, but it may belimited to be less than the maximum number of hardware streams that thedivision allows. The stream mapper 150 assigns a defined, small basenumber of streams (e.g., one hardware stream) to each namespace. Theremaining hardware streams are assigned to the namespaces based on aproportion of the logical streams for the namespaces. It is noted thatthe even and proportional scheme may collapse into a fair and balancedscheme as the base number of the hardware streams increases towardsfloor=integer [(number of hardware streams)/(number of namespaces)]. Theeven and proportional scheme is similar to a proportional scheme but canensure that all namespaces are assigned with at least one hardwarestream first, and the most populous namespace can be assigned with allor a large portion of the remaining hardware streams.

FIG. 4 shows an example even and proportional scheme for assigninglogical streams to hardware streams, according to one embodiment. Inthis example, the namespace NS1 has 1 logical stream, the namespace NS2has 2 logical streams, the namespace NS3 has 8 logical streams, thenamespace NS4 has 4 logical streams, the namespace NS5 has 1 logicalstreams, and the namespace 6 has 1 logical streams. The stream mapper150 assigns a base (even) number of hardware streams (e.g., one hardwarestream) to each of the namespaces to provide a low-level, basicstreaming capability to each namespace, and further assigns theremaining hardware streams based on the proportion (e.g., unweighted orweighted proportion) of the logical streams (minus the 1 for hardwarestream already distributed). In the present example, the namespace NS2is assigned with one hardware stream, the namespace NS3 is assigned withsix hardware streams, and the namespace NS4 is assigned with threehardware streams among the remaining ten hardware streams, assumingsimilar throughput for each of the logical streams, i.e., unweightedproportion.

According to another embodiment, the stream mapper 150 can map logicalstreams based on a hybrid auto-streaming scheme. The stream mapper 150reserves a certain number of hardware streams forsharing/merging/coalescing namespaces, thereby assigning one hardwarestream to more than one namespaces (herein also referred to as a“trans-namespace” assignment). The trans-namespace hardware streams arereserved for I/O traffic patterns that can span multiple namespaces. Thestream mapper 150 can also use an auto-streaming logic to detect suchtrans-namespace streams to merge and assign a common hardware stream.The stream mapper 150 can then assign the remaining hardware streams tothe namespaces based on one of the previously described assignmentschemes such as a fair and balanced scheme, a proportional scheme, andan even and proportional scheme. The trans-namespace assignment may bedifferentiated from namespace clustering explained above with referenceto FIG. 3B in that in the hybrid auto-streaming scheme, the namespaceclustering is intentional and directly configurable from the start. Thatis, the amount of shared hardware streams, the namespaces that belong tothem, and/or the data qualities that allow for inclusion in the hardwarestreams can optionally be defined by the host, and can be performedbefore the data storage drive analyzes how the remaining hardwarestreams are to be divided. In other words, in the hybrid auto-streamingapproach, namespaces may be grouped into shared hardware streams as afirst step, then the remaining hardware streams are distributed viaother approaches, whereas in the “fair and balanced,” “proportional,”and “even and proportional” approaches, the clustering is only done as alater step, after the bulk of the hardware streams have already beenassigned via the primary approach.

FIG. 5A shows an example of a hybrid auto-streaming scheme, according toone embodiment. In this example, there are eight hardware streams andeight namespaces. It is noted that the number of hardware streams andthe namespaces may be the same or different. The auto-streaming logic ofthe stream mapper 150 may determine that the namespaces NS6, NS7, andNS8 are behaviorally coupled and can assign three (or any applicablenumber, as the host or auto-streaming detector may determine) hardwarestreams to the namespaces NS6, NS7, and NS8. Then, each of thenamespaces NS1, NS2, NS3, NS4, and NS5 is independently assigned withone of the remaining hardware streams. The three shared hardware streamsmay not be tied to a specific namespace. Instead, the three sharedhardware streams are used to efficiently perform I/O operations thatspan the namespaces NS6, NS7, and NS8. As a more specific example, thenamespaces NS6, NS7, and NS8 may each have multiple logical streams; andeach of those logical streams within a given namespace may be directedinto one of the three shared hardware streams.

FIG. 5B shows an example of a hybrid auto-streaming scheme, according toanother embodiment. In this example, there are 16 hardware streams andeight namespaces. It is noted that the number of hardware streams andthe namespaces may be the same or different. Each of the namespacesNS1-NS8 is respectively assigned with one hardware stream. Theauto-streaming logic of the stream mapper 150 may reserve the remainingeight hardware streams for auto-streaming for operations that can spanmultiple namespaces. The hardware streams reserved for auto-streamingmay be useful for cases when the I/O operation is not specified with anidentifier of a specific namespace indicating that the I/O operations isa trans-namespace operation. A distribution similar to this may beuseful in cases where the namespaces each contain several logicalstreams, some of which are similar in nature to those of the othernamespace, and some of which are unique in nature to that namespace. Theunique logical streams of each namespace can use the individual hardwarestreams dedicated to the namespace, and the logical streams that aresimilar to those of other namespaces can the utilize the shared hardwarestreams.

When a namespace (or namespace cluster) is added, removed, or changedsubstantially, the present stream mapping scheme may be rerun. If thereis a change to the namespaces that use the currently assigned hardwarestreams, the stream mapper can re-run the mapping scheme to redistributehardware streams, and the new and unassigned namespaces may be assignedwith hardware streams based on a new mapping scheme. When the hardwarestreams are re-distributed, the mapping scheme may change from onemapping scheme to another mapping scheme. For example, an even andproportional scheme may switch to a fair and balanced scheme as the basenumber of the hardware streams increases.

FIG. 6 is a flowchart of an example fair and balanced mapping scheme,according to one embodiment. A host can configure the stream mapper tooperate in a fair and balanced mode (601). Alternatively, the streammapper can monitor the I/O traffic pattern and configures itself tooperate in a fair and balanced mode based on the number of availablehardware streams, the number of namespaces, the number of logicalstreams per each namespace, etc. The stream mapper calculates a floorvalue and checks if the floor value is greater than or equal to one(602). If the floor is greater than or equal to one, the stream mapperassigns a fair number of hardware streams to each namespace (i.e., fairassignment) (611) and assigns the remaining hardware streams to thenamespaces based on a number of logical streams (i.e., balancedassignment) (612). If the floor value is not greater than or equal toone, the stream mapper analyzes I/O traffic patterns for each namespaceand merges namespaces based on the I/O traffic patterns to createnamespace clusters (621). The merging process continues until the numberof namespace clusters is equal to or less than the number of availablehardware streams (622). The stream mapper assigns a fair number ofhardware streams to each namespace cluster (i.e., fair assignment)(623).

FIG. 7 is a flowchart of an example proportional mapping scheme,according to one embodiment. A host can configure the stream mapper tooperate in a proportional mode (701). Alternatively, the stream mappercan monitor the I/O traffic pattern and configures itself to operate ina fair and balanced mode based on the number of available hardwarestreams, the number of namespaces, the number of logical streams pereach namespace, etc. The stream mapper assigns hardware streams tonamespaces based on a proportion of logical streams (702). If there areany namespaces that are unassigned with hardware streams (703), thestream mapper monitors completed logical streams of namespaces that areassigned with hardware streams (704) and checks if any hardware streamsare freed (705). The stream mapper reassigns the freed hardware streamsto the unassigned namespaces (706). In one embodiment, the stream mappermonitors general I/Os of the namespaces using a general I/O stream. Whena namespace (or namespace cluster) is added, removed, or changedsubstantially, the stream mapper can re-run the mapping scheme, and thehardware streams can be re-distributed.

FIG. 8 is a flowchart of an example even and proportional mappingscheme, according to one embodiment. A host can configure the streammapper to operate in an even and proportional mode (801). Alternatively,the stream mapper can monitor the I/O traffic pattern and configuresitself to operate in a fair and balanced mode based on the number ofavailable hardware streams, the number of namespaces, the number oflogical streams per each namespace, etc. The stream mapper assigns afirst even number of hardware streams to each namespace (i.e., fairassignment) (802). The stream mapper further assigns any remaininghardware streams to the namespaces based on a proportion distribution(i.e., proportional assignment) (803).

FIG. 9 is a flowchart of an example hybrid auto-streaming mappingscheme, according to one embodiment. A host can configure the streammapper to operate in a hybrid auto-streaming mode (901). Alternatively,the stream mapper can monitor the I/O traffic pattern and configuresitself to operate in a fair and balanced mode based on the number ofavailable hardware streams, the number of namespaces, the number oflogical streams per each namespace, etc. The stream mapper monitors I/Otraffic patterns (902) and determines if there are any namespaces thatcan be behaviorally coupled (903). Behaviorally coupled namespaces mayhave logical streams that have the same or similar write sequentiality,lifespan, timing pattern, I/O size, a file type, and/or I/O trafficpatterns. If there are any behaviorally coupled namespaces, the streammapper assigns a base number of hardware streams to the behaviorallycoupled namespaces (911) and further assigns the remaining hardwarestreams to each of non-coupled namespaces for auto-streaming (912). Ifthere is no behaviorally coupled namespaces, the stream mapper assigns abase number of hardware streams to each namespace (921) and assigns theremaining hardware streams to the namespaces for auto-streaming amongthe namespaces (922).

According to one embodiment, a method includes: receiving logicalstreams from a plurality of namespaces; determining characteristics oflogical streams associated with the plurality of namespaces; selecting aconfigurable assignment mode; and assigning the logical streamsassociated with the plurality of namespaces to a plurality of hardwarestreams to access physical storage blocks associated with a data storagedevice based on the characteristics of the logical streams and theconfigurable assignment mode. A number of hardware streams to access thephysical storage blocks associated with the data storage drive is fixed,and a number of logical streams associated with the plurality ofnamespaces is varied depending on I/O processes running on a hostcomputer.

The characteristics of the logical streams may include a writesequentiality, a lifespan, a timing pattern, an I/O size, a file type, anumber of logical streams per each namespace, a proportion of thelogical streams per each namespace, and input/output (I/O) trafficpatterns of the logical streams.

The configurable assignment mode may be a fair and balanced mode, andthe method may further includes: calculating a floor value to determinewhether a number of hardware streams is greater than or equal to anumber of namespaces; if the floor value is greater than or equal toone, assigning a fair number of hardware streams to each namespace andassigning remaining hardware streams to the namespaces based on thenumber of logical streams for each namespace; and if the floor value isless than one, analyzing the I/O traffic patterns for each namespace bycollectively analyzing the I/O traffic patterns of the logical streamsthat belong to each namespace and merging namespaces having same orsimilar I/O traffic patterns into one or more namespace clusters;assigning a fair number of hardware streams to each namespace cluster.

The namespaces may be clustered until the number of namespace clustersis equal to or less than the number of hardware streams.

The configurable assignment mode may be a proportional mode, and themethod may further include: assigning the hardware streams to thenamespaces based on a weighted proportion of logical streams for eachnamespace. The weighted proportion for the logical streams may becalculated based on I/O throughput and a number of logical streams.

The configurable assignment mode may be an even and proportional mode,and the method may further include: assigning a first number of hardwarestreams to each namespace; and assigning the remaining hardware streamsto the namespaces based on a weighted proportion of the logical streamsfor each namespace. The weighted proportion for the logical streams maybe calculated based on I/O throughput and a number of logical streams.

The configurable assignment mode may be a hybrid auto-streaming mode,and the method may further include: monitoring the I/O traffic patternsassociated with the logical streams; determining whether there arebehaviorally coupled namespaces based on the I/O traffic patterns.

The method may further include: assigning a base number of hardwarestreams to behaviorally coupled namespaces; and assigning the remaininghardware streams to each namespace that is not behaviorally coupled forauto-streaming.

The method may further include: assigning a base number of hardwarestreams to each namespace if there are no behaviorally couplednamespaces; and assigning remaining hardware streams to the namespacethat are behaviorally coupled for auto-streaming.

According to another embodiment, a data storage device includes: aplurality of data storage blocks; and a stream mapper configured to:receive logical streams from a plurality of namespaces; determinecharacteristics of logical streams associated with the plurality ofnamespaces; select a configurable assignment mode; and assign thelogical streams associated with the plurality of namespaces to aplurality of hardware streams to access the plurality of data storageblocks based on the characteristics of the logical streams and theconfigurable assignment mode. A number of hardware streams to access thephysical storage blocks associated with the data storage drive is fixed,and a number of logical streams associated with the plurality ofnamespaces is varied depending on I/O processes running on a hostcomputer.

The data storage device may be a solid-state drive (SSD) implementedwith an auto-streaming feature.

The characteristics of the logical streams may include a writesequentiality, a lifespan, a timing pattern, an I/O size, a file type, anumber of logical streams per each namespace, a proportion of thelogical streams per each namespace, and input/output (I/O) trafficpatterns of the logical streams.

The configurable assignment mode may be a fair and balanced mode, andthe stream mapper may be further configured to: calculate a floor valueto determine whether a number of hardware streams is greater than orequal to a number of namespaces; if the floor value is greater than orequal to one, assign a fair number of hardware streams to each namespaceand assign remaining hardware streams to the namespaces based on thenumber of logical streams for each namespace; and if the floor value isless than one, analyze the I/O traffic patterns for each namespace bycollectively analyzing the I/O traffic patterns of the logical streamsthat belong to each namespace and merge namespaces having same orsimilar I/O traffic patterns into one or more namespace clusters; andassign a fair number of hardware streams to each namespace cluster.

The namespaces may be clustered until the number of namespace clustersis equal to or less than the number of hardware streams.

The configurable assignment mode may be a proportional mode, and thestream mapper may be further configured to: assign the hardware streamsto the namespaces based on a weighted proportion of logical streams foreach namespace. The weighted proportion for the logical streams may becalculated based on I/O throughput and a number of logical streams.

The configurable assignment mode may be an even and proportional mode,and the stream mapper may be further configured to: assign a firstnumber of hardware streams to each namespace; and assign the remaininghardware streams to the namespaces based on a weighted proportion of thelogical streams for each namespace. The weighted proportion for thelogical streams may be calculated based on I/O throughput and a numberof logical streams.

The configurable assignment mode may be a hybrid auto-streaming mode,and the stream mapper may be further configured to: monitor the I/Otraffic patterns associated with the logical streams; and determinewhether there are behaviorally coupled namespaces based on the I/Otraffic patterns.

The stream mapper may be further configured to: assign a base number ofhardware streams to behaviorally coupled namespaces; and assign theremaining hardware streams to each namespace that is not behaviorallycoupled for auto-streaming.

The stream mapper may be further configured to: assign a base number ofhardware streams to each namespace if there are no behaviorally couplednamespaces; and assign remaining hardware streams to the namespace thatare behaviorally coupled for auto-streaming.

The above example embodiments have been described hereinabove toillustrate various embodiments of implementing a system and method formapping streams to storage blocks based on namespaces. Variousmodifications and departures from the disclosed example embodiments willoccur to those having ordinary skill in the art. The subject matter thatis intended to be within the scope of the invention is set forth in thefollowing claims.

What is claimed is:
 1. A method comprising: receiving logical streamsfrom a plurality of namespaces; determining characteristics of logicalstreams associated with the plurality of namespaces; selecting aconfigurable assignment mode; and assigning the logical streamsassociated with the plurality of namespaces to a plurality of hardwarestreams to access physical storage blocks associated with a data storagedevice based on the characteristics of the logical streams and theconfigurable assignment mode, wherein a number of hardware streams toaccess the physical storage blocks associated with the data storagedrive is fixed, and a number of logical streams associated with theplurality of namespaces is varied depending on I/O processes running ona host computer.
 2. The method of claim 1, wherein the characteristicsof the logical streams include a write sequentiality, a lifespan, atiming pattern, an I/O size, a file type, a number of logical streamsper each namespace, a proportion of the logical streams per eachnamespace, and input/output (I/O) traffic patterns of the logicalstreams.
 3. The method of claim 1, wherein the configurable assignmentmode is a fair and balanced mode, and the method further comprises:calculating a floor value to determine whether a number of hardwarestreams is greater than or equal to a number of namespaces; if the floorvalue is greater than or equal to one, assigning a fair number ofhardware streams to each namespace and assigning remaining hardwarestreams to the namespaces based on the number of logical streams foreach namespace; and if the floor value is less than one, analyzing theI/O traffic patterns for each namespace by collectively analyzing theI/O traffic patterns of the logical streams that belong to eachnamespace and merging namespaces having same or similar I/O trafficpatterns into one or more namespace clusters; assigning a fair number ofhardware streams to each namespace cluster.
 4. The method of claim 3,wherein the namespaces are clustered until the number of namespaceclusters is equal to or less than the number of hardware streams.
 5. Themethod of claim 1, wherein the configurable assignment mode is aproportional mode, and the method further comprises: assigning thehardware streams to the namespaces based on a weighted proportion oflogical streams for each namespace, wherein the weighted proportion forthe logical streams is calculated based on I/O throughput and a numberof logical streams.
 6. The method of claim 1, wherein the configurableassignment mode is an even and proportional mode, and the method furthercomprises: assigning a first number of hardware streams to eachnamespace; and assigning the remaining hardware streams to thenamespaces based on a weighted proportion of the logical streams foreach namespace, wherein the weighted proportion for the logical streamsis calculated based on I/O throughput and a number of logical streams.7. The method of claim 1, wherein the configurable assignment mode is ahybrid auto-streaming mode, and the method further comprises: monitoringthe I/O traffic patterns associated with the logical streams;determining whether there are behaviorally coupled namespaces based onthe I/O traffic patterns.
 8. The method of claim 7, further comprising:assigning a base number of hardware streams to behaviorally couplednamespaces; and assigning the remaining hardware streams to eachnamespace that is not behaviorally coupled for auto-streaming.
 9. Themethod of claim 7, further comprising: assigning a base number ofhardware streams to each namespace if there are no behaviorally couplednamespaces; and assigning remaining hardware streams to the namespacethat are behaviorally coupled for auto-streaming.
 10. A data storagedevice comprising: a plurality of data storage blocks; and a streammapper configured to: receive logical streams from a plurality ofnamespaces; determine characteristics of logical streams associated withthe plurality of namespaces; select a configurable assignment mode; andassign the logical streams associated with the plurality of namespacesto a plurality of hardware streams to access the plurality of datastorage blocks based on the characteristics of the logical streams andthe configurable assignment mode, wherein a number of hardware streamsto access the physical storage blocks associated with the data storagedrive is fixed, and a number of logical streams associated with theplurality of namespaces is varied depending on I/O processes running ona host computer.
 11. The data storage device of claim 10, wherein thedata storage device is a solid-state drive (SSD) implemented with anauto-streaming feature.
 12. The data storage device of claim 10, whereinthe characteristics of the logical streams include a writesequentiality, a lifespan, a timing pattern, an I/O size, a file type, anumber of logical streams per each namespace, a proportion of thelogical streams per each namespace, and input/output (I/O) trafficpatterns of the logical streams.
 13. The data storage device of claim10, wherein the configurable assignment mode is a fair and balancedmode, and the stream mapper is further configured to: calculate a floorvalue to determine whether a number of hardware streams is greater thanor equal to a number of namespaces; if the floor value is greater thanor equal to one, assign a fair number of hardware streams to eachnamespace and assign remaining hardware streams to the namespaces basedon the number of logical streams for each namespace; and if the floorvalue is less than one, analyze the I/O traffic patterns for eachnamespace by collectively analyzing the I/O traffic patterns of thelogical streams that belong to each namespace and merge namespaceshaving same or similar I/O traffic patterns into one or more namespaceclusters; and assign a fair number of hardware streams to each namespacecluster.
 14. The data storage device of claim 13, wherein the namespacesare clustered until the number of namespace clusters is equal to or lessthan the number of hardware streams.
 15. The data storage device ofclaim 10, wherein the configurable assignment mode is a proportionalmode, and the stream mapper is further configured to: assign thehardware streams to the namespaces based on a weighted proportion oflogical streams for each namespace, wherein the weighted proportion forthe logical streams is calculated based on I/O throughput and a numberof logical streams.
 16. The data storage device of claim 10, wherein theconfigurable assignment mode is an even and proportional mode, and thestream mapper is further configured to: assign a first number ofhardware streams to each namespace; and assign the remaining hardwarestreams to the namespaces based on a weighted proportion of the logicalstreams for each namespace, wherein the weighted proportion for thelogical streams is calculated based on I/O throughput and a number oflogical streams.
 17. The data storage device of claim 10, wherein theconfigurable assignment mode is a hybrid auto-streaming mode, and thestream mapper is further configured to: monitor the I/O traffic patternsassociated with the logical streams; and determine whether there arebehaviorally coupled namespaces based on the I/O traffic patterns. 18.The data storage device of claim 17, wherein the stream mapper isfurther configured to: assign a base number of hardware streams tobehaviorally coupled namespaces; and assign the remaining hardwarestreams to each namespace that is not behaviorally coupled forauto-streaming.
 19. The data storage device of claim 17, wherein thestream mapper is further configured to: assign a base number of hardwarestreams to each namespace if there are no behaviorally couplednamespaces; and assign remaining hardware streams to the namespace thatare behaviorally coupled for auto-streaming.